Features
Features:

Product Tour >

Edraw AI >

Paid Plans:

Individuals >

Business >

Eduaction >
Resources
Blog

History

How-tos & Tips

Discovery

Biography

Business Analysis

Examples

AI concept Map

Free AI Mind Map Generator

Onenote Mind Map

Bcg Matrix Examples

Nike Marketing Strategy

Unilever SWOT Analysis

Make Mind Maps in Google Docs

Guide

FAQs

What's New

Resource Center
Templates
All Templates

Brain Storming Templates

Strategy and Planning Templates

Project Management Templates

Product Management Templates

Human Resources Templates

Agile Workflow Templates

Marketing Templates

Education Templates

Fun and Games Templates

User Gallery
Download
Pricing
Enterprise

MindMap Gallery Natural Medicinal Chemistry Sugars and Glycosides-Physical and Chemical Properties, Glycoside Bond Cleavage

Natural Medicinal Chemistry Sugars and Glycosides-Physical and Chemical Properties, Glycoside Bond Cleavage

This is a mind map about natural medicinal chemistry, sugars and glycosides - physical and chemical properties, glycoside bond cleavage. Sugars and glycosides are common components in natural products and have a variety of biological activities. Understanding their physical and chemical properties is of great significance for studying the extraction, isolation and purification of natural products.

Edited at 2024-01-16 20:26:17

PlotWizard

Recent works View more works>>

Natural Medicinal Chemistry Sugars and Glycosides-Physical and Chemical Properties, Glycoside Bond Cleavage

PlotWizard

Recent works View more works>>

Recommended to you
Outline

Natural Medicinal Chemistry Sugars and Glycosides-Structure Determination, Extraction and Isolation
- 35
PlotWizard
Natural Medicinal Chemistry Sugars and Glycosides - Overview, Configuration and Classification
- 25
PlotWizard

sugars and glycosides

Classification of glycosides

Classification

glycoside atom

aglycone

According to terminal carbon configuration

Alpha glycosides are mostly L-type, and β-glycosides are mostly D-type.

According to the number of connected monosaccharides

According to the number of sugar chains

According to the existence in the organism

primary glycoside

Glycosides originally present in plants

secondary glycosides

The primary glycoside hydrolyzes away a sugar or changes its structure

oxyglycoside

Alcohol glycosides

It is a glycoside formed by dehydration of alcoholic hydroxyl group and sugar terminal hydroxyl group.

Salidroside (strength, enhance adaptability), ranunculus (insecticide, bactericidal), geniposide (laxative, choleretic), glycyrrhizic acid (anti-tumor)

Phenolic glycosides

It is a glycoside formed through a phenolic hydroxyl group

Gastroside (sedative), sennoside A (diarrhoea), rutin (blood vessel softening), cinpidin (antibacterial)

ester glycosides

The aglycon is connected to the terminal carbon of the sugar by -COOH.

It has the properties of ester and acetal.

cyanogenic glycoside

alpha-hydroxycyanoside

HCN is produced in the body to exert an antitussive effect. Overdose → death; taking lactose → competes for β-glucosidase in the body → prevents poisoning and increases LD50

γ-Hydroxycyanoside

Trichoside: Reduces alanine aminotransferase

oxyazoglycosides

Indole glycosides

Glucosinolates

Glucosinolate, sinigrin, white sinigrin

nitrogen glycosides

Adenosine (A), guanosine (G), cytidine (C), uridine (U), crotonin

Carbon glycoside

Mainly flavonoids, chalcones, anthraquinones, anthrones, phenolic acids, etc.

Physical and chemical properties of sugar

physical properties

Solubility

Sugar: Small molecules are highly polar and have good water solubility; monosaccharides are more polar than disaccharides; water solubility decreases as the degree of polymerization increases. Glycoside: hydrophilic; aglycon: lipophilic

Chemical properties (identifying reactions!)

oxidation reaction

Activity order of monosaccharide groups

Hemiacetals (ketones) > Primary alcohols > Secondary alcohols 2-OH > 3,4-OH e bond -OH > a bond -OH (*general chemical shift value e bond > a bond)

Reaction conditions and products

• -CHO→-COOH Silver mirror reaction: Ag →Ag Flynn reaction: Cu2 →Cu2O brick red↓ Br2/H2O: fade • HNO3: Aldose→glycaric acid • HIO4, Pb(Ac)4 oxidation: ortho-diol-OH

periodic acid reaction

Reaction rate: ortho-diol>α-amino alcohol>α-hydroxyaldehyde (ketone)> ortho-dione

Reaction conditions: aqueous solution, protected from light

Reaction characteristics: The reaction proceeds quantitatively, the degradation products are stable, and the generated iodic acid can be titrated

Determination of periodic acid consumption

Monosaccharide: determined by Fischer formula; glycoside: determined by Haworth formula; active CH2: consume one more molecule of periodic acid

Pb(Ac)4 oxidation

Stronger oxidizing ability than HIO4: oxalic acid can be oxidized at room temperature Higher stereoselectivity: cannot oxidize furanose trans-diol OH Need to be carried out in organic solvents

glycoaldehyde formation reaction

Polysaccharides and glycosides are first hydrolyzed into monosaccharides under the action of concentrated acid, and then dehydrated to form corresponding products.

Molish reaction

Sample Concentrated sulfuric acid α-naphthol → brown ring

hydroxyl reaction

Reactivity: Hemiacetal hydroxyl group (C1-OH) > Primary alcohol group (C6-OH) > Secondary alcohol group (C2-OH)

reaction type

Etherification

Esterification

Acetalization

Concept: Aldehydes or ketones react with hydroxyl groups with appropriate spatial positions under the action of dehydrating agents to form cyclic acetals and ketals.

Sugar acetone → five-membered ring ketal (isopropylidene derivative)

Sugar Benzaldehyde → Six-membered cyclic acetal (benzaldehyde derivative)

carbonyl reaction

Reducing sugar phenylhydrazine → glycohydrazone (easily soluble in water) 2 molecules of phenylhydrazine → glycohydrazone (hardly soluble in water)

Boric acid complex reaction

The ortho-di-OH of sugar can form complexes with many reagents → change the physical constants → help sugar Isolation, identification and configuration derivation of

Sugar Boric acid → Complex (increased acidity, ionizable)

Cleavage of glycoside bonds (hydrolysis types, mechanisms and reaction rules)

acid catalyzed hydrolysis

The glycoside bond belongs to an acetal structure and is easily hydrolyzed by dilute acid catalysis.

Mechanism: The glycoside atom is protonated first, and the bond is broken to generate a cationic ion or a semi-chair intermediate, which is solvated in water to form a sugar.

The general rule of hydrolysis: the electron cloud density of the glycoside atom is ↑, the protonation steric hindrance is ↓, and the ring tension is ↑ (stability ↓), the easier the reaction is.

Specific rules (from easy to difficult)

Glycoside atoms: N > O > S > C glycoside Glycoside bond configuration: when the aglycone is a small group, e > a; when the aglycone is a large group, a > e Aglycone: phenolic glycoside, enol glycoside > alcohol glycoside, alcohol glycoside: tertiary OH > secondary OH > primary OH -I effect of substituents: 2,3-dideoxysugar > 2-deoxysugar > 3-deoxysugar > hydroxyl sugar > uronic acid > 2-aminosugar Furanose > Pyranose; Ketose > Aldose (stability, tonicity) Sugar has many A bonds: easy (stability) C5-Substituent size: The larger, the more difficult it is (protonation steric hindrance): five-carbon sugar > methyl five-carbon sugar > six-carbon sugar > seven-carbon sugar

acetolysis reaction

Reagents: acetic anhydride acid (H2SO4, HClO4, CF3COOH, Lewis acid)

Reaction mechanism: CH3CO is the attacking group

Purpose: Protect the -OH on the aglycone and increase lipophilicity; partially crack the glycoside bond: identify the connection method of polysaccharides

Reaction rule: isomerization is easy to occur (end group of sugar, sugar cis-C2, 3-OH); reaction rate: (1→6)>>(1→4) >> (1→3) >> (1 →2)

base catalyzed hydrolysis

Generally, glycoside bonds are stable to dilute bases, but there are electron-withdrawing groups on the aglycone that directly interact with glycoside atoms. Continuous, easily hydrolyzed by alkali

Product: C1-OH and C2-OH are trans and easily hydrolyzed to 1,6-glucose anhydride

Hydrolysis products can be used to determine the configuration of glycoside bonds

beta-elimination reaction

Sugar reducing end, free CO (β, γ positions of glycoside bond) → activate ortho-H • Elimination reaction with 3-O- or 4-O-glycoside bonds • Alkali peels off the monosaccharides at the reducing end of the polysaccharide one by one and has no effect on the non-reducing end. • What is produced is α-deoxysugar acid

Understand the substitution patterns of reducing sugars from the generated sugar acids

Enzymatic hydrolysis

Purpose: Determine the glycoside bond configuration; the obtained aglycone keeps its structure unchanged; when extracting and separating, be careful to kill enzymes and preserve the glycoside! The hydrolysis methods that can obtain the real aglycone after hydrolysis are: enzymatic hydrolysis and oxidative cracking. Invertase can hydrolyze β-fructosidic bonds; maltase can hydrolyze α-glucosidic bonds; cellulase can hydrolyze β-glucoside; helicase can hydrolyze β-glucosidic bonds; amygdalin can hydrolyze β-6C aldoside

Oxidative cracking method (Smith degradation method)

Reagents: HIO4 (NaIO4) NaBH4 dilute H

The reaction conditions are mild and protoglycone can be obtained Not applicable to aglycones containing ortho-diol OH Can be used for the hydrolysis of C glycosides (Smith cleavage of carbon glycosides: obtain CHO-containing carbon source) Ginsenoside: Smith degrades to obtain protoglycone; use HOAc to flip the configuration; use HCl to form a ring

Selective hydrolysis of uronic acid glycosides

Special methods are required (photolysis method, Pb(Ac)4 decomposition method, acetic anhydride-pyridine decomposition method, microbial culture method)

Hydrolysis of glycosides linked to ether bonds cannot yield aglycone: paeoniflorin